text: The CL vortex force is
  with  the (Lagrangian) Stokes drift velocity and vorticity  (i.e. the curl of the Eulerian mean-flow velocity ). Further  is the fluid density and  is the curl operator. 
  The CL vortex force finds its origins in the appearance of the Stokes drift in the convective acceleration terms in the mean momentum equation of the Euler equations or Navier–Stokes equations. For constant density, the momentum equation (divided by the density ) is:
  with
  * (a): temporal acceleration
  * (b): convective acceleration
  * (c): Coriolis force due to the angular velocity  of the Earth's rotation
  * (d): Coriolis–Stokes force
  * (e): gradient of the augmented pressure
  * (f): Craik–Leibovich vortex force
  * (g): viscous force due to the kinematic viscosity 
  The CL vortex force can be obtained by several means. Originally, Craik and Leibovich used perturbation theory. An easy way to derive it is through the generalized Lagrangian mean theory. It can also be derived through a Hamiltonian mechanics description.